The present invention relates to methods and apparatus for packaging electroni equipment and more particularly to a card cage which can accomodate printed circuit cards of different size.
Packaging requirements for electronic equipment often impose conflicting requirements on the chassis employed to house printed circuit (PC) cards. Electronic chassis are commonly provided which employ backplanes having electronic connectors. PC cards are typically mechanically retained and supported within the chassis and have connectors which interface with respective backplane connectors mounted on the backplane.
The overall dimensions of a chassis are usually selected to permit the utilization of the largest size board employed in the system. For example, to accommodate certain complex electronic functions on a single PC card, chassis are usually specified so as to accommodate a PC card having an area adequate to mount all necessary electronic and mechanical components needed to implement the respective electronic functions. While this sizing technique is perfectly adequate when all PC boards employed within a chassis are of the same type or when all PC boards within a chassis have a complexity which requires approximately the same board area to implement the relevant electronic functions, oftentimes, the board area requirements vary substantially between board types. The utilization of a common board size to accommodate all electronic functions within a specific card cage or chassis results in substantial waste of board space and reduced packing density since less complex functions must be implemented on the board having an area specified to accommodate the largest board area within the system. Alternatively, separate chassis have been provided to accommodate different board sizes. This technique adds undesirable mechanical complexity and cost to the system packaging.
For the above reasons, it would be desirable to have a card cage which was sufficiently flexible to permit the utilization of PC cards of different size within a single card cage.